Electric switch



Sept .26, 1944- J. w. sAMzELlUs 2,359,159

ELECTRIC SWITCH Filed Jan. 29, 1943 INVENTOR WITNESSES:

A'rro EY Jobh W Samzelzzzi Patented Sept. 26, 1944 UNITED STATES PATENT OFFICE Westinghouse lElectric & Manufacturing Company, East Pittsburgh, Pa., ac'orporation of Pennsylvania Application Janary-29, 1943, Serial No.'473,919

'5 Claims. (C1. 20D- 162) My invention relates, generally, to electric switches and, more particularly, to `electr-ic switches of the knife-blade type.

In knife-blade switches of certain types, particularly those which are enclosed in cabinets, the

switch blades are mechanically connected to an operating crank by means of hooks or links -made from nber or other insulating material. The hooks are riveted onto the blades in pairs, one o'n each side of the blade. Although this would appear to be a strong construction, both mechanically and electrically, the hooks have sometimes failed after a switch has been installed in service.

One feature of the present design which may be responsible for some of the trouble is the heat insulating property ofthe insulating material of which the hooks are composed. Since the area of the blade covered by the hooks is approximately 50% of the total radiating surface, a great deal of heat is retained in the blades, thereby causing their temperature to rise. Excessive heat is detrimental to the fiber material and its strength may be greatly reduced by the heat in theblade long before there are any visible signs i of charrng.

Also, the rough edges resulting from the punching operation in the manufacture of the hooks reduce the dielectric strength by providing surfaces which will absorb moisture and permit dirt and dust to accumulate and lodge. The reduction of the dielectric strength of the insulating material may result in a breakdown of the insulation after the switch is in service.

An object of my invention, generally stated, is to provide an electric switch which shall be simple and eiiicient in operation and which may be economically manufactured and installed.

A more specific object oi my invention is to provide an improved means for connecting a switch blade to the operating crank of the switch.

Another object of my invention is to provide a connecting device which shall be mechanically strong and shall have a high dielectric strength.

A further object of my invention is to provide a device for connecting a switch blade to the operating crank of the switch which shall not increase the temperature of the blade.

Still another object of my invention is to provide a connecting device which shall be suitable for use with switch blades of a different thickness.

Other objects of my invention will be explained fully hereinafter or will be apparent to those skilled in the art.

1n accordance with my invention, a switch blade is connected to its operating crank by means of an insulating block moulded from a shock resisting material. The block is provided with a slotted opening for receiving the crank and is bolted down against the upper edge of the blade by means of two bolts threaded into a metal yoke that may be inserted through an elongated hole in the blade.

For a fuller understanding of the nature and objects oilmy invention, reference may be had to `the following detailed description, taken in conjunction with the accompanying drawing in which:

Figure 1 is a View, in perspective, oi an electric switch embodying my invention;

2 is a View, in section, of one of the switch blade connectors; and

Fig. 3 is a view, in perspective, of a modiication of the structure shown in Fig, 1.

Referring to the drawing, and particularly to Fig. l, the structure shown therein comprises a base VI0 on which three switch blades II are mounted, thereby constituting a three-pole switch. One end of each one of the blades Il is disposed in a hinge jaw I2 and the other end is disposed to engage a brake jaw I3. The blades are simultaneously actuated by an operating 'crank or bail I4 which is mounted in bearing blocks I5 and I6.

In order to mechanically connect the operating crank I4 to the switch blades and 'electrically insulate it from the blades, an individual connector ll is provided for each one of the blades. Each connector Il comprises a block i8 preferably molded from an insulating material having a high dielectric strength as well as being capable oi resisting severe shock. A slot I9 is provided in one side of the block I8 transversely of the blade Il for receiving the operating crank I4.

As shown more clearly in Fig. 2, the block I?! is bolted down against the upper edge of the blade II by two bolts 2| which extend through holes 22 provided in the block I8. The bolts 2i are threaded into a short and strong metal yoke 23 which is disposed transversely of the blade through an elongated hole 24 located approximately in the center of the blade. The bolts 2l are spaced at a distance only slightly greater than the thickness of the blade I I, thereby holding the insulating block I8 and the blade Il together very rigidly. If preferred, the yoke 23 may be placed across the bottom of the blade by merely increasing the length of the bolts 2l. In this case it will not be necessary to provide the hole 24 in the blade II.

In order that the vsame insulating block may be used for blades oi a different thickness,Y a shallow V-groove 25 may be provided inthe bottom of the block I8 and a similar V-shaped groove 26 may be provided in the top of the yoke 23. lIhe grooves 25 and 26 will aid in centering and xing the positon of the block on the blade.

A soft metal plate 21 may be provided under the heads of the bolts 2|. After the bolts are securely tightened, corners 28 of the plate 21 may Vbe turned up to prevent the bolts 2l from be-v coming loose. v

The molded block I8 will retain'its dielectric strength inasmuch as all of its surfaces are smooth and highly polished. Furthermore, it has a high mechanical strength because of its mass and because of the Ycompressive loading by the bolts 2I. v

Since the block I3 is mounted on top of the switch blade and practically none of the radiating surface of the blade is covered by the block, 'the dissipation of the heat produced in the blade is not retarded. Therefore, the temperature of the blade is not increased by the insulating block I8, as was the case with the insulating hooks of the type previously utilized.

As illustrated in the modiiication shown in Fig. 3, all the switch blades maybe tied together by means of an insulating bar 29 disposed on top of the blocks I8 underneath the metal plates 21. The utilization of the bar 29 is considered desirable for multiple Vswitches requiring a long operating crank I4, since some of the loading on the crank is relieved by the bar 29. As explained hereinbefcre, the yoke 23 may be disposed at the bottom of each blade instead of being inserted through an opening in the blade. This arrangement is also illustrated in Fig. 3.

From the foregoing description it is apparent that I have provided an insulating connector which is simple in construction, mechanically strong and which Will havea long life in operating service. Furthermore, the present connector is so mounted on the switch blade that the operating efficiency of the switch is in no Way impaired.

I do not desire to be restricted to the particular form or arrangement of parts herein shown and described, since it is evident that they may be changed and modied Without departing from the spirit and scope of my invention as dened inthe appended claims.

I claim as my inventioni l* 1. A connector for connecting a switch operating member to a switch blade comprising, a substantially rectangular block of insulating material having a slot disposed in one side thereof forY receiving the operating member, and means extending longitudinally of the block and cooperating with means disposed transversely of the blade for securing one end of the block on one edge of the blade.

2. A connector for connecting a switch operating member to a switch blade comprising, a substantially rectangular block of insulating material having a slot disposed in one side thereof for `receiving the operating member, and means extending longitudinally through the block and cooperating with means disposed transversely of the blade for securing one end of the block on one edge of the blade.

3. A connector for connecting a switch operating member to a switch blade comprising, a substantially rectangular block of insulating material having a slot disposed in one'side thereof for receiving the operating member, and means extending Vlongitudinally through the block and Y to secure one end of the block on one edge of the blade.

5. A connector for connecting a switch operating member to a switch blade comprising, a substantially rectangular block of insulating material having a slot disposed in one side thereof for receiving the operating member, a yoke Vdisposed transversely of the blade, and means extending longitudinally through the block on each side of the blade and cooperating with the yoke to secure one end of the block on one edge of the blade, said yoke having a groove therein for re ceiving the blade. Y

JOHN W. SAMZELIUS. 

